Adhesive closing part, method for producing the same device for implementing said method

ABSTRACT

The invention relates to an adhesive closing part, especially for foaming upholstery parts of car seats during production of the latter, comprising adhesive elements ( 10 ) arranged on one side for connection to corresponding adhesive elements of another adhesive closing part by forming an adhesive closure and connecting elements on the other side of the adhesive closing part for producing a connection to the corresponding foam material. A reliable and high-strength connection to the foam material is achieved due to the fact that the connecting elements consist of an adhesive medium, especially a fluorine gas, applied at least on the other side of the adhesive closing part.

The invention involves a fastening part, especially for the foaming ofcushion parts in the manufacture of vehicle seats, with adhesiveelements on the one side to link with corresponding adhesive elements ofanother fastening part forming a fastening and with one connectingelement in the nature of a fastening medium on the other side of thefastening part for the making of a connection with the respective foammaterial. The invention also involves a process for the manufacture of afastening part to that effect as well as a device for the application ofthe process.

Fastening parts in a general form are known through EP 0 612 485,whereby the fastening part is laid in a foam form so that the bondingagent, in the form of loop elements on the backside of the adhesiveclosure part, comes into contact with the pertinent foam material, so asto produce a firm bond with it. The opposite front side of the adhesiveclosure part has adhesive elements in the form of bonding hooks,adhesives heads, mushroom-shaped bodies, or the like, which areprotected from the penetration of foam material, for example, asdescribed in the European document, in that they are surrounded, ontheir entire surface, by an uncrosslinked thermoplastic. If after thefoaming process in the mold and the removal of the foamed part, thecover is removed, the adhesive elements are free and can later be joinedwith adhesive elements of another adhesive closure part, for example, inthe form of a loop strip, with the formation of a common adhesiveclosure.

In this way, it is possible to affix, for example, upholstery coveringmaterials on the foamed upholstery parts of a vehicle seat or anairplane seat or to join rotating components, for example, in the formof grinding wheels with tool rests, to traditional grinders andapparatuses. The aforementioned foam material can definitely be thinlyliquid, as a function of the object to be formed, and have viscositieswhich are in the range of water or below. It has become evident thatwhen using looping or noose-like material as a bonding agent or evenwhen using a nappy cloth or the like, the nooses, which are, in fact,open, are not completely penetrated by the foam material, but ratherform a kind of barrier for it, which inhibits the penetration of thefoam material. In the subsequent hardening or baking process for thefoam material, there are voids then—that is, gaslike hollow occlusions,which work against a firm bonding between the adhesive closure part andthe foam material, at the transition sites between the looping materialand the foam. As a result of such reduced strength of the bondingbetween the fastening parts and foam material in particular incontinuous stress it comes to a loosening of the connection and thefastening part pulls apart from the foam material, which in all leads tothe unusability of the entire component, for example in the shape of avehicle seat or grinding wheel adapter.

A general fastening part is known through EP-A-0809 952, which iscomposed of a biologically degradable synthetic material. In the knownsolution, the individual adhesive elements are formed of neighboringfacing double-hook elements each of which has a reinforcing rib on theside facing the band-like fastening part. On the other side of thefastening part as a connecting element, a medium is arranged in the formof a water-soluble resin-like material, which after penetration of waterforms a kind of separate adhesive layer on the fastening material,without thereby putting into question the biodegradability of the entirefastening. The application of an independent adhesive layer as anadhesive medium on the side of the fastening part turned away from theadhesive elements is also the object of EP-A-0754 416. In this knownsolution, the adhesive application as an adhesive medium to that endoccurs through a coating process. It has been shown, however, thatindependently of the selection of adhesive no good connection comes intobeing between the fastening part and the foam material and that inparticular in the subsequent stressing of the foam material it comes toa pulling apart and hence to a loosening of the connection between thefastening part and the foam material.

Based on this state of the art, the invention has the function offurther improving a fastening part so that a more secure andhigh-strength connection is achieved between the fastening part and therespective foam material that is used. Furthermore the invention has thefunction of making available a process for the manufacture of afastening part to that end as well as a device for the application ofthis process. A task to this end is resolved by a fastening part withthe features of claim 1, a process with the features of claim 3, and adevice with the features of claim 5.

Because the adhesive medium is fluorine in accordance with thecharacterizing part of claim 1, it comes to a high-strength connectionbetween the fastening part so treated and the respective foam material,which is detachable only with difficulty, so that the result is also along-lasting secure connection between the fastening part and the laterfoam body. Through the adhesive medium that penetrates into thefastening part and is incorporated into this part, a surface-selectivechemical reaction is produced on the fastening part that leads to goodconnection values with the foam material. In contrast to the knownsolutions, the adhesive medium is not applied separately to thefastening material as a kind of adhesive layer but is a laid-incomponent of the fastening.

For a specialist in the area of fastening and foaming technology, it issurprising that through the introduction of a gaseous adhesive medium onthe fastening part he can achieve a better link with the foam materialthan by means of the known looped materials or through the usualadhesives that are expensive and hence cost-intensive in production andin which the loops, for example, spatially penetrate and push forwardfar into the foam material. Instead of a mechanical hooking of looped ornoose-like material with the foam, an adhesion to the foam material isproduced by means of the individually introduced adhesiveness mediumduring its production with heat and pressure, which leads to higherstrength values with the desired bonding.

If fluorine is used as the gaseous adhesiveness medium to be introduced,preferably with adhesive closure parts made of polyolefin material, thehydrogen atoms fixed on the polyolefin surface are replaced by fluorineatoms. This substitution reaction takes place at room temperature. Astarting or initial reaction is not required. The hydrocarbons, whichare then partially fluorinated on the surface, behave completelydifferent from the previous base material of the adhesive closure part.As a result of its high electronegativity, the fluorine atom tries tofill its outer electron shell. To this end, electrons are drawn awayfrom adjacent carbon and hydrogen atoms. Therefore, one speaks of aninduced polarity, which with the main base, constitutes the goodadhesion with the foam material, preferably made of polyurethane foam.

An advantage of the fluorine treatment is a process-reliable adhesionwith all polyolefins with an otherwise low surface tension, whereinthere is a uniform penetration with the fluorine material, so thatcomplicated configurations and surfaces, including back cuts, hollowspaces, interior surfaces, or the like, also obtain a fluorine treatmentwhich favors adhesion. In order to attain as good as possible bondingvalues for the foam material, one has to take care that there is asufficient number of polar fractions, wherein with polyolefin materials,polar fractions of 40 mN/m² and more are attained.

With the method in accordance with the invention for the production of aclosure part with the previously designated features, the fluorine isapplied in a nitrogen atmosphere, wherein the introduction of fluorine,continuously or discontinuously—with a moving or stationary adhesiveclosure part—can be effectively carried out. The storage offluorine-nitrogen mixtures in high-pressure tanks has been the state ofthe art for many years and, as concerns the toxicology of such a gasmixture, it is similarly and safely regulated in safety data sheets andDIN standards, so that even with a large-scale use, there should be noworries about health risks.

With an apparatus in accordance with the invention for the carrying outof the previously described method, the adhesive closure parts to betreated are exposed to the fluorine-nitrogen gas atmosphere in a reducedpressure chamber. With the reduced pressure chamber, one can safelyprevent the undesired emission of the fluorine-nitrogen gas mixture fromthe apparatus.

Such an apparatus can carry out a discontinuous method, in which theadhesive closure parts to be treated remain stationary in the apparatusfor a prespecified time, or it can carry out a continuous method, inwhich an introduction and discharge of a continuous strip or a surfaceof an adhesive closure part takes place continuously.

In the following, the claimed invention is explained with the aid of thedrawing in more detail. In a schematic representation, not drawn toscale, the FIGURE exhibits a longitudinal section through the apparatuswith which it is possible to carry out the method of the invention toproduce the claimed adhesive closure parts, in accordance with theinvention.

The adhesive closure part, shown below, is used, in particular, forfoamed upholstery parts of vehicle seats (not shown) during theirproduction. The strip-like or sheet-like adhesive closure part has, onone side, adhesive elements 10 for bonding with corresponding adhesiveelements of another adhesive closure part (not shown), with theformation of a common adhesive closure. The adhesive closure part shownin the FIGURE is produced by means of a common method, as shown forexample by DE 196 46 318 A1. On the other side or on the underside ofthe adhesive closure part, a bonding agent is provided to produce abonding with the pertinent foam material, for example, in the form of apolyurethane, which is introduced backwards into the adhesive closurepart. The adhesive closure part itself is formed from apolyolefin-plastic material, wherein polyolefins are generally theall-embracing designation for polymers of the following generalstructure:

in which R¹ can mostly stand for hydrogen and R² for hydrogen, astraight-chain or branched, saturated, aliphatic or a cycloaliphaticgroup. Occasionally, polymers with aromatic groups, for example, thephenyl radical (R²C₆H₅, see polystyrene) are also counted among thepolyolefins. Products with R¹═H are also designated as poly(α-olefin)s;they can be considered vinyl polymers.

Polyolefins with great industrial importance in the field of adhesiveclosures are, for example, polyethylenes, polypropylenes, polybutenes,which are also occasionally, erroneously, called polybutylenes orpolybutenes, as well as polyisobutenes and poly(4-methyl-1-pentene)s.Polymers of the higher α-olefins, for example, 1-polyhexene,1-polyoctene, or 1-polyoctadecene, however, have had only very limitedindustrial application in this field up to now. Among the polyolefinsare also copolymers of various olefins, for example, those of ethylenewith propylene.

The adhesiveness medium is preferably fluorine and is introduced intothe adhesive closure part via a subsequent fluorination. Theaforementioned fluorine is used as F₂ and hence as gas, preferably in anitrogen atmosphere.

Preferably, the introduction of the fluorine gas at 3% is undertaken, inaccordance with the method of the invention, at room temperature and areduced pressure of ca. 650 mbar. Such a method is continuouslyoperated, which will be explained in more detail later. With adiscontinuous introduction method, a temperature of 40° to 50° C. ispreferably selected and the fluorine charge is increased to 10% in thenitrogen atmosphere.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view of an embodiment of the apparatusaccording to the present invention.

The apparatus according to the invention, as it is represented in thedrawing, has a reduced pressure chamber 12, in which the adhesiveclosure parts are exposed to a fluorine-nitrogen gas atmosphere (F₂/N₂).Within the reduced pressure chamber 12, a guide roller 14 can pivot withthe rotating direction in accordance with the represented part. On theupper side, the reduced pressure chamber 12 closes off in a connectingsite 16, to which the discharge pump (vacuum pump), which is notdepicted in more detail, is connected. Via such a connecting site 16, itis possible to adjust the desired reduced pressure, for example 650mbar, within the reduced pressure chamber 12. Furthermore, roomtemperature should prevail in the reduced pressure chamber 12. Moreover,the reduced pressure chamber 12 has an entry 18 and an exit 20 for theuntreated and for the adhesive closure part treated with fluorine.

In the transporting direction of the adhesive closure part 10, which isindicated with arrows, a first deflection roller 22 is located rightbehind the entry 18 and a second deflection roller 24, right before theexit 20. Such two deflection rollers 22,24 permit a direction deflectionof the adhesive closure part in such a way that the individual adhesiveelements 10 can mesh with recesses, which are not depicted in moredetail, on the surface of the guide roller 14, so as to be able to atleast partially withdraw, in such a way, from the fluorine-nitrogenatmosphere. Such introduction of the fluorine gas into the adhesiveclosure part therefore takes place predominantly along its back side,which is noose-free and which is to later produce the bonding with thefoam material of the part to be foamed. The entry 18 and the exit 20 arelocated at a uniform level, moving in a horizontal direction. Thematerial transport speed for the strip-like adhesive closure part ispreferably 20 m/min and for such continuous method operation, 3%fluorine (F₂) is dissolved in the nitrogen atmosphere. For adiscontinuous operation, for which the guide roller 14 is stopped, thetemperature in the interior of the reduced pressure chamber 12 ispreferably increased to 40° to 50° C., and the gaseous fluorine chargeis increased to 10%. As a result of the adjusted reduced pressure in thereduced pressure chamber 12, the fluorine-nitrogen gas mixture cannotexit.

Insofar as it is provided for the entire adhesive closure part to befurnished with fluorine, this plays no part while foaming, inparticular, so long as the adhesive elements 10 are covered, in theform, for instance, of a separable film or the like. In such a case, theapplication of foam to the adhesive elements 10 is effectively avoidedby the covering and bonding with the foamed material takes place onlyacross the rear side of the respective closure part treated in this way.

What is claimed is:
 1. Process for manufacturing a fastening part for afoam material having adhesive elements on one side of the fastening partto connect with corresponding adhesive elements of another fasteningpart, and a connecting element in the nature of an adhesive medium onthe other side of the fastening part to produce a connection with thefoam material, wherein the adhesive medium is a laid-in component of thefastening part and consists of fluorine, said process comprising thefollowing step: applying a fluorine gas in a nitrogen atmosphere;wherein the applying step is a continuous operation with 3 percentfluorine at room temperature and at a reduced pressure.
 2. Process inaccordance with claim 1, wherein the reduced pressure is 650 mbar. 3.Process for manufacturing a polyolefin fastening part for a foammaterial having adhesive elements on one side of the fastening part toconnect with corresponding adhesive elements of another fastening part,and a connecting element in the nature of an adhesive medium on theother side of the fastening part to produce a connection with the foammaterial, wherein the adhesive medium is a laid-in component of thefastening part and consists of fluorine, said process comprising thefollowing step: applying a fluorine gas in a nitrogen atmosphere;wherein the applying step is a continuous operation with 3 percentfluorine at room temperature and at a reduced pressure.
 4. Process inaccordance with claim 3, wherein the reduced pressure is 650 mbar. 5.Process for manufacturing a fastening part for a foam material havingadhesive elements on one side of the fastening part to connect withcorresponding adhesive elements of another fastening part, and aconnecting element in the nature of an adhesive medium on the other sideof the fastening part to produce a connection with the foam material,wherein the adhesive medium is a laid-in component of the fastening partand consists of fluorine, said process comprising the following step:applying a fluorine gas in a nitrogen atmosphere; wherein the applyingstep is a discontinuous operation with 10 percent fluorine at 40 to 50°C. and at a reduced pressure.
 6. Process in accordance with claim 5,wherein the reduced pressure is 650 mbar.
 7. Process for manufacturing apolyolefin fastening part for a foam material having adhesive elementson one side of the fastening part to connect with corresponding adhesiveelements of another fastening part, and a connecting element in thenature of an adhesive medium on the other side of the fastening part toproduce a connection with the foam material, wherein the adhesive mediumis a laid-in component of the fastening part and consists of fluorine,said process comprising the following step: applying a fluorine gas in anitrogen atmosphere; wherein the applying step is a discontinuousoperation with 10 percent fluorine at 40 to 50° C. and at a reducedpressure.
 8. Process in accordance with claim 7, wherein the reducedpressure is 650 mbar.